In quilting, a top and bottom layer of fabric are sewn together, with a layer of a batting material interposed between the fabric layers. Quilting was once conducted completely by hand-stitching on the material, using a frame that places the material between a pair of take-up rolls.
Recently, the trend has been to mount a sewing head, either as a part of a conventional sewing machine or as a part of a “long arm” machine, on a hand-guided translation device, that is, a device translatable in the X and Y directions relative to the frame or table. A benefit of this system is the increased speed and efficiency of the sewing machine over manual stitching. The translation device usually comprises two carriages: a cross carriage movable on the table in a first direction (usually longitudinal on the table) and a sewing carriage movable on the cross carriage in a second direction, the second direction being orthogonal to the first direction (and usually referred to as “transverse”). On most of the long-arm machines, a sewing arm is equipped with a pair of axles to constitute the sewing carriage; in other situations, a sewing arm is fixedly mounted atop a carriage member to constitute the sewing carriage. A quilting frame or table providing this type of a translation device is referred to as a hand-guided quilting table or frame.
Even with the hand-guided quilting frame available, there is a continuing desire to increase the speed, efficiency and reproducibility of the increasingly-complex stitching patterns. By equipping the quilting frame with mechanical drive means for moving the sewing head relative to the material to be quilted, the reproducibility permitted by the computer can be realized. A quilting frame equipped in this manner is described as a computerized hand-guided frame. The sewing head of such a device may be hand-guided in a manual mode or computer-guided in a computerized or automatic mode. In the hand-guided mode, the sewing head is moved manually relative to the workpiece, which requires free motion of the translation device in at least one of the X and Y directions. In the computer-guided mode, the sewing head is moved relative to the workpiece in a pre-programmed pattern, based upon a control signal. This requires computer control of the translation device, usually through motors mounted remotely from the part being moved, the action of the motors being transmitted by the use of timing belts, steel wires and the like. In practical circumstances, an operator will frequently be switching from hand-guided operation to computerized operation and vice versa.
Some of the existing systems for computerizing have a “cable car” mode of operation, in which at least one of the motors for driving a moving part of the translation device is mounted on the table or fame. This drive motor is then mechanically linked to the cross carriage by a timing belt, steel wires, pulleys, etc. On the cross carriage itself, the drive motor used to drive the sewing carriage is located on the cross carriage and mechanically linked to the sewing carriage by timing belts, etc. The belt/wire design causes some difficulty in installation, as the length of belts and ropes must be carefully matched with the tables and carriages and belt/wire tensioners are needed to minimize movement errors.
In another known system, a self-propelled unit is positioned on the table adjacent to the translation device of the existing quilting device and a pair of orthogonal means on the self-propelled unit are mechanically connected to the corresponding carriages on the translation device. This requires careful coordination and matching of the “sidecar” unit to the translation device to make effective mechanical connection. In one case, the system uses a rack-and-pinion type of drive mechanism on the table (X-direction), with the rack portion thereof matching the physical dimensions of the table. Practically, a specific design of such a self-propelled unit, its translation means and the table rack is required for each different table/translation device combination. Further, the footprint of the table occupied by the sidecar unit effectively reduces the work area that may be reached by the sewing head.
All of these systems are characterized by one common feature—the driving motors are mounted remotely to the system being driven. Further, all of these systems have the disadvantage of the time and effort needed to switch between the hand-guided and computerized modes, which is required relatively frequently. The change entails removing bolts or pins that attach the carriage and the sewing arm to the timing belts or wires.
It is therefore an unmet need of the prior art to provide a means for automatically switching between automatic and manual modes, that is, engaging/disengaging the drive motors automatically.